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US3205355A - Moisture gage standards - Google Patents

Moisture gage standards Download PDF

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Publication number
US3205355A
US3205355A US266963A US26696363A US3205355A US 3205355 A US3205355 A US 3205355A US 266963 A US266963 A US 266963A US 26696363 A US26696363 A US 26696363A US 3205355 A US3205355 A US 3205355A
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Prior art keywords
gage
standard
paper
radiation
standards
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Expired - Lifetime
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US266963A
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English (en)
Inventor
Ralph C Ehlert
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General Electric Co
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General Electric Co
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Filing date
Publication date
Priority to US143749A priority Critical patent/US3150264A/en
Application filed by General Electric Co filed Critical General Electric Co
Priority to US266963A priority patent/US3205355A/en
Priority to GB778/64A priority patent/GB1055111A/en
Priority to NL6402829A priority patent/NL6402829A/xx
Priority to DE19641498762 priority patent/DE1498762A1/de
Priority to SE3465/64A priority patent/SE315761B/xx
Application granted granted Critical
Publication of US3205355A publication Critical patent/US3205355A/en
Anticipated expiration legal-status Critical
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • G01N22/04—Investigating moisture content
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3554—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for determining moisture content
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/34—Paper
    • G01N33/346—Paper sheets
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3554—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for determining moisture content
    • G01N21/3559—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for determining moisture content in sheets, e.g. in paper

Definitions

  • FIG. 3 E /as E Q s 1 E 22 P V o as 54 a; 56 z 2 A (mcnons) FIG. 3
  • This invention relates to checking and standardizing instruments that use radiant energy for measuring the water content of a sheet of paper at some stage during the paper making process.
  • the invention is directed to the preparation and use of standards that simulate the combined efiect of the water and paper on the radiation so they may be substituted for wet paper in order to check the stability of the instrument at desired intervals.
  • the invention is applicable to instruments that employ electromagnetic radiation to measure continuously the amount of a Water sorbed by an organic material.
  • Examples of such instruments are those which couple microwave, visible light or infrared radiation with the material being gaged so that detected difierences in the amount of radiation transmitted through the material or back scattered, reflected or otherwise attenuated by it serves as an indication of variations in the water content of the material.
  • a handicap of this procedure is that the sample exchanges moisture with the atmosphere very rapidly. Hence, it must be transported to the laboratory in a sealed container and hastily analyzed in a controlled environment in order to get a satisfactory measurement. If a variance is found between actual moisture and the amount measured in the laboratory, many thousands of feet of paper, whose moisture content is erroneously determined, will have traversed the machine during the test period. If the operator is provided with knowledge about the amount of error, he still has no convenient way for introducing the proper correction except by trial and error that necessitates additional tests in order to be sure that the gage is reading properly.
  • a general object of the present invention is the provision of a means and method for conveniently standardizing a gage of the character mentioned above.
  • a more specific object is to provide standards that may be substituted for the material in which the quantity of water is being measured and which will produce gage ice readings corresponding with a definite quantity of water in the material, to the end that the gage readout may be checked for precision and accuracy.
  • a further object of this invention is to illustrate use of the concept of selecting a material for a standard which is different than either the sorbed substance or the material being gaged but which simulates the combined effect of the substance and material on the radiant energy being used in the gage.
  • An adjunct of this object is the provision of standards that are essentially unaffected over long periods of time by changes in environmental conditions such as temperature, humidity, physical state or by any other environmental effects that would change the value their output signals when they are substituted in the gage from time to time.
  • this object entails use of standard materials that exhibit the same vibrationalrotational resonance phenomenon, absorption and reflectance as does the material being gaged.
  • the invention is applicable to gages that either transmit or reflect radiation from the material whose water content is being measured.
  • gages that either transmit or reflect radiation from the material whose water content is being measured.
  • use of the new standards will be described in connection with a gage that employs infrared radiation to measure the quantity of water in organic materials such as cellulosic paper or textiles.
  • infrared radiation in two specific Wavelength bands is reflected from the surface of the material. Pulses of a radiation in each band are consecutively de tected and a continuous waveform electric signal is produced. This is amplified and converted to a D.-C. signal in a demodulator whose output voltage magnitude is related to the amount of moisture present in paper.
  • FIG. 1 - is a schematic representation of an infrared or visible radiation gage that is especially suitable for measuring moisture content in paper and textiles.
  • FIG. 2 is a cross-section of a reference standard employing the principles of the present invention.
  • FIG. 3 is a wavelength-intensity distribution curve that is useful for explaining the invention.
  • FIG. 1 there is shown a sheet of paper 10 which may be traversing a paper making machine at speeds up to 2500 feet per minute. It is desired to determine the moisture content of a paper on a continuous basis.
  • the paper making machine not shown, is provided with heaters for removing more or less water from the paper, depending on whether it is too wet or too dry.
  • Electric signals that are indicative of the moisture content of the paper as measured by the gage may be used to control heat or moisture application as required or the quantity of moisture may merely be determined visually through a meter or recorder, not shown, but which may 3 be connected to output terminals 11 at the right side of FIG. 1.
  • a schematic representation of the gage head is seen to include an incandescent lamp 12 and a collimating lens 13 which projects a parallel beam of light toward paper 10.
  • a pair of interference filters 14 and 15 which are mounted on a rotatable wheel 16. Filters 14 and 15 are preferably 'placed near the center of rotation so that one or the other of them will be in the beam Without interruption. Wheel 16 may be rotated at revolutions per second by any suitable motor means, not shown. With this arrangement, pulses of infrared radiation at the two different Wavelengths impinge on the upper surface of paper 10 in rapid succession.
  • the filters 14 may be selected to pass a band centered at 1.94 microns infrared radiation and another at 1.80 microns, respectively. Radiation in each band is refiected from the surface of the paper and their separate intensities are detected by a detector 17 which is shown as a photocell but which may be any suitable infrared detector such as a solid state lead sulphide cell.
  • 1.94 micron infrared radiation is chosen because it coincides with an absorption band of water sorbed by paper. This means that the amount of this radiation that is reflected by the paper will vary in accordance with water content and the electric signals from detector 17 will vary accordingly.
  • the 1.80 micron band is chosen because it is apart from an absorption band for water and its reflected intensity is, therefore, relatively unaffected by changes in water content.
  • the shorter wavelength radiation serves as a reference since its magnitude will change substantially only due to causes other than variations in water content, such as fluctuations in the intensity of the light source 12 or changes in the distance between the source and the paper.
  • Disk 16 is provided with a substantially semi-circular slot 18 which passes a beam of light directly from source 12 to another photocell 19. The purpose of this is to provide another signal for synchronously demodulating the alternating signals produced by photocell 17.
  • An integrating sphere may also be used for collecting the reflected radiation viewed by photocell 17.
  • the output signals from photocells 17 and 19 are amplified in their respective preamplifiers 20 and 21.
  • Preamplifiers 20, 21; photocells 17, 19; disks 16; filters 14 and 15; collimating lens 13; and light source 12 constitute an entity designated a gage head.
  • This apparatus may be suitably mounted in a stationary position over paper 10 or it may be adapted to traverse over the width of the paper if desired. The traversing mechanism is not shown because it is not essential to understanding the present invention.
  • Omitted from the gage head are the shields which prevent extraneous light from being sensed by detector 17 or 19.
  • Emerging from preamplifier 20 is a continuous train of electric signals of essentially semi-sinusoidal form.
  • the first in the series of pulses may be due to the intensity of radiation from the long wavelength and the second may be due to the short wavelength radiation which is reflected from the paper.
  • These consecutive pulses are fed over a cable, which may be 40 feet or more long, to
  • variable gain amplifier 23 is adapted to produce the same level of output signal regardless of the magnitudes of the input signals.
  • the proportionality between the consecutive pulses is maintained although their net difference is increased in the process of amplification.
  • Part of the alternating output from amplifier 23 is used to stabilize it through the agency of D.C. feedback accomplished with a device 44 that includes a filter-rectifier combination.
  • the output from amplifier 23 is further amplified in a tuned amplifier 24 which feeds into a demodulator 25. The latter also receives synchronizing signals from detector 19 in the gage head.
  • demodulator 25 includes a paraphase amplifier from which cathode and plate signals are taken that are out of phase with each other. These signals operate a synchronous relay, not shown, through whose contacts the alternating waves from tuned amplifier 24 is passed into an integrating circuit not shown.
  • the integrating circuit produces a D.-C. output voltage which is applied to a dividing resistance 26 that has an adjustable contact 27 and a smoothing capacitor 28.
  • the position of contact 27 determines the slope of the calibration line of the gage. That is, its adjustment affects the slope of the line that represents the relation betwen output voltage and percent moisture in the paper.
  • Means are also provided for establishing the initial or zero point of the gage output. These includes a D.-C. source 29 in series with a limiting resistor and a switch 30 which are connected across a potentiometer 31 on which there is an adjustable arm 32. It can be seen readily that the position of contact arm 32 determines the amount of voltage that opposes the voltage derived from. potentiometer 27 so that a zero point or zero moisture condition can be pre-set. The net output signal, this is indicative of the amount of water in the paper, appears on terminals 11 which may be connected with a direct reading meter, a recorder or other electro responsive device, not shown.
  • the conventional procedure for calibrating gages of this type is to insert a series of samples ranging from dry to wet in the beam, noting their corresponding output signals on a recorder, and then quickly determining their moisture content in the laboratory by weighing, drying, re-weighing and subtracting the weights. It is readily apparent that this procedure may be tolerable at initial installation, but it would not be convenient nor desirable to repeat the performance each time the operator wants to make a determination of whether the gage is reading precisely as it did at original calibration.
  • the present invention proposes to provide stable standards that can be used at any time to check and compare the output of the gage with its original calibration.
  • a suitable standard must cause the same output signal by the gage at any time in the life of the gage. It must be unaffected by time or changes in its environmental condition such as in temperature or humidity. When presented to the gage head it must have the same effect as the combination of the substance and the material being gaged rather than just the substance alone. It must be rugged and unaffected by physical handling.
  • the standard should include a compound or radical that a vibrationalrotational resonance quality that is comparable with the resonant band for the combination of the water and material being measured.
  • the total effect of the standard should be the same as the effect of the water and ma terial being gaged. Moreover, it is usually desirable that at least two standards be provided, one for checking calibration corresponding with low percentages of water and another for high percentages, to the end that the gage may be checked near the limits of its operating range.
  • the standard holder may take the form of a counterbored disk 33 of a metal such as aluminum.
  • the reference standard material 34 may be deposited in a recess as shown and an infrared transmitting window such as glass 35 or other transparent non-hygroscopic material may be placed over it.
  • an adhesive On shoulder 36, which supports glass 35 at its margin, there may be applied an adhesive that maintains the moisture tight integrity of the standard.
  • a suitable adhesive is known by the trade name Hysol sealant and is an epoxy resin material.
  • metal disk 33 is about five inches in diameter and the reference standard material 34 constitutes a pellet of about two inches in diameter.
  • the pellet 34 may be formed bodily with disk 33 in a hydraulic press or it may be formed separately and mounted in other containers such as thermal setting plastics.
  • the pellet may also be set in a resilient material that lines a recess, such as that in which it resides in FIG. 2, and the glass window may press the pellet against the resilient material.
  • Many suitable containers for hermetically sealing a reference standard should now suggest themselves. The proper design for a standard holder will, of course, depend upon the type of gage in which it is to be utilized.
  • a pair of standards is required, one for low percentages of the substance in the material and the other for high percentages. This facilitates establishing the proper slope of the calibration curve. It is also necessary to have different pairs of standards for different ranges of water and different types of paper. For example, different standards are required for measuring water in kraft paper than are required for water in facial tissue or newsprint with an infrared gage. If the gage is one that uses infrared radiation at two different wavelengths as does the one described above, the standard should simulate the effect of the waterpaper combination for both Wavelengths.
  • a suitable low range standard consisted of about a three square inch pellet of bismuth hydroxide formed with a total load of 10,000 pounds.
  • Other suitable hydroxides for simulating different percentages of water in papers having basis weights dissimilar to tissue are the hydroxides of sodium, magnesium, calcium, lithium, zinc, cesium, indium, potassium and platinum. This enumeration may not be all inclusive but it is believed to include materials for standards which would cover a wide range of moisture contents for papers of various compositions.
  • a pure bismuth hydroxide standard is used to simulate the conditions which are equivalent to kraft paper having a four percent moisture content, for example. This is considered the low standard in view of the gage being adapted 6. to read moisture contents over the range of zero to 15 percent of total weight of water with respect to water plus paper.
  • a suitable high standard for simulating kraft paper was made by mixing four percent of zinc hydroxide and ninety-six percent of magnesium oxide by weight and pelletizing the mixture at about three thousand pounds per square inch.
  • the usual range of hydroxide required for both high and low standards is one to ten percent of hydroxide with respect to the total weight of hydroxide and filler.
  • a fundamental rule is that the amount of filler to be used is that which causes the standard to yield a readout value within the range of the gage.
  • Suitable high moisture content standards have been made with hydrated salts mixed with another material. Because of their water of hydration, the hydrated salts exhibit intense absorption at the 1.94 band and as such they are not suitable for standards by themselves. They are useful, however, for making very easily controlled standards by mixing them in various proportions with nonhydrated magnesium oxide.
  • a good high standard was made of magnesium sulphate having seven molecules of Water of hydration with magnesium oxide filler. Mixtures of different salts, hydroxides and fillers may also be employed to obtain exact duplication of some paper-water combinations.
  • Other hydrated salts that may be formed into a standard with magnesium oxide or other fillers are as follows:
  • any hydrated salt that is stable in the intended environment which may be as high as C. in a paper making machine, and which gives the desired gage output for the wavelengths at which it operates, will be suitable.
  • FIG. 3 there is shown a graph of the percentage of reflected infrared radiation versus infrared wavelength in microns for a typical standard material. It will be observed that when this standard is in the beam, the reflected intensity of the shorter wavelength is not greatly different than the reflected intensity of the longer wavelength radiation. The standard is designed so that these intensities agree very closely with the intensities obtained for the same Wavelengths when the material being gaged is in the primary infrared beam. Thus, the successive pulses due to the different wavelengths detected by photocell 17 are essentially the same height whether the standard or the sample being measured is in the gage. By plotting intensity versus wavelength curves, as in FIG. 3, for various quantities of sample substances or mixtures thereof,
  • the curve representing reflectivity or backscatter of the standard is relatively flat in the region of the reference wavelength, 1.80 microns, which means that the intensity from the standard remains sufficiently constant even if there is some difference between wavelengths that are passed in different gages.
  • the curve dips in the region of the moisture measuring wavelength, probably due to resonance of the water of hydration or the hydroxyl radical in the standard. It is desirable that the standard be designed so that the relatively flat bottom part of the dip coincides with the measuring wavelength. Otherwise minor shifts in the wavelength would cause greater than desired intensity changes and this would make it more difiicult to use the same standard in another gage even though it be of essentially the same character.
  • the essence of the invention is the making of standards that yield a comparable effect, when placed in the gage head, as does the material whose moisture content is being gaged.
  • any compound that includes a radical or complex which has a resonance characteristic that produces the net effect, by itself or in combination with other materials, of water in the material being gaged for the type of radiation used in the gage fulfills the basic concept of the invention.
  • Standards may be made in forms other than those discussed above. For instance, it is not imperative that the standard material be pelletized for it can be used in powdered form in a container such as that shown in FIG. 2. When a powdered material is used, however, it is necessary to compact it sufliciently so that its surface condition will not be altered due to handling or this will give inconsistent results when the reference is inserted in the gage head on different occasions. To overcome this difficulty and to meet the standard requirements in particular cases, it has been found advantageous to entrain some standard materials in a plastic or viscose matrix.
  • the matrix may have different coefiicients of refraction and reflection than the standard material, it is desirable to minimize losses in some cases by underlying the sample material 34 with a radiation reflecting substance so that most of the radiation comes out of the reference standard container.
  • the standard material 34 may be placed on a reflecting surface 37 if it is desired to increase the reflected radiation output. Copper, silver, gold, chromium and most metals are good infrared radiation reflectors. On the other hand, if transmission of the radiation through the specimen being gaged is to be simulated, a reflecting surface is not necessary.
  • the same material can be used for both the high and low standards by making the layer 34 rather thin and using a reflecting surface 37 for one part of the range and omitting it for another.
  • the thickness of the standard material 37 may be governed to some extent by type of radiation employed in the gage and whether it involves an essentially surface or depth phenomenon.
  • the customary procedure for calibrating a moisture gage on the customers premises is to place a series of paper samples with varying moisture contents in the beam and noting gage readout for each. After measurement, each samples precise moisture content is determined by the method of taking differences between wet and dry weights.
  • the plot of moisture content against readout is the calibration curve.
  • the readouts may be obtained from a chart recorder which may be connected to output terminals 11 in FIG. 1 and which has its own Zero, sensitivity and range controls. In the course of calibrating, the high and low moisture content simulating standards are placed in the gage and their respective readouts may be taken with a voltmeter across terminals 11.
  • said container means including a transparent window means that transmits radiation into and out of the compound.
  • said container means including a transparent window means that transmits radiation into and out of the mixture.
  • said container means including a transparent window means that transmits radiation into and out of the mixture.

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US266963A 1961-10-09 1963-03-21 Moisture gage standards Expired - Lifetime US3205355A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US143749A US3150264A (en) 1961-10-09 1961-10-09 Infrared reflection and absorption system for measuring the quantity of a substance that is sorbed in a base material
US266963A US3205355A (en) 1963-03-21 1963-03-21 Moisture gage standards
GB778/64A GB1055111A (en) 1963-03-21 1964-01-07 Moisture gage standards
NL6402829A NL6402829A (de) 1963-03-21 1964-03-17
DE19641498762 DE1498762A1 (de) 1963-03-21 1964-03-18 Eichnormale fuer Messgeraete fuer die Bestimmung eines Feuchtigkeitsgehaltes in organischen Traegern
SE3465/64A SE315761B (de) 1963-03-21 1964-03-20

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US266963A US3205355A (en) 1963-03-21 1963-03-21 Moisture gage standards

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US3205355A true US3205355A (en) 1965-09-07

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US266963A Expired - Lifetime US3205355A (en) 1961-10-09 1963-03-21 Moisture gage standards

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US (1) US3205355A (de)
DE (1) DE1498762A1 (de)
GB (1) GB1055111A (de)
NL (1) NL6402829A (de)
SE (1) SE315761B (de)

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452193A (en) * 1965-04-19 1969-06-24 Weyerhaeuser Co Moisture content measuring method and apparatus
US3478210A (en) * 1967-08-23 1969-11-11 Gen Electric Extended range infrared moisture gage standards
US3512895A (en) * 1967-02-06 1970-05-19 Eastman Kodak Co Spectroreflectrometric reference standard and method
US3631246A (en) * 1970-04-30 1971-12-28 Shell Oil Co Method for determining the purity of recovered sylvite
US3641349A (en) * 1969-09-29 1972-02-08 Measurex Corp Method for measuring the amount of substance associated with a base material
US3790796A (en) * 1972-06-05 1974-02-05 Infra Systems Inc Method and apparatus for measurement of sheet opacity
US4037970A (en) * 1972-08-24 1977-07-26 Neotec Corporation Optical analyzer for agricultural products
US4040747A (en) * 1972-08-24 1977-08-09 Neotec Corporation Optical analyzer for agricultural products
US4082950A (en) * 1977-02-10 1978-04-04 Loew's Theatres, Inc. Calibration assembly for infrared moisture analyzer
US4095105A (en) * 1977-02-03 1978-06-13 Neotec Corporation Standardizing test sample
US4398541A (en) * 1978-05-25 1983-08-16 Xienta, Inc. Method and apparatus for measuring moisture content of skin
US4438500A (en) 1973-07-20 1984-03-20 Cem Corporation Rapid volatility analyzer
US4694165A (en) * 1985-09-30 1987-09-15 Gamma-Metrics Bulk material analyzer calibration block
US4715715A (en) * 1984-11-06 1987-12-29 Measurex Corporation System for measuring the color of a material
USRE32861E (en) * 1973-07-20 1989-02-07 Cem Corporation Automatic volatility computer
US20060028647A1 (en) * 2004-08-06 2006-02-09 Mark Howard L Gray optical standard
WO2017031569A1 (en) 2015-08-27 2017-03-02 Honeywell Limited Holmium oxide glasses as calibration standards for near infrared moisture sensors

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2122768A (en) * 1982-06-18 1984-01-18 Infrared Eng Calibration standard for infrared absorption gauge
GB9518100D0 (en) * 1995-09-05 1995-11-08 Infrared Eng Calibration standard for infrared absorption gauge

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US1014601A (en) * 1911-11-28 1912-01-09 Matthew M Looram Receptacle.
US2667425A (en) * 1950-02-02 1954-01-26 Presque Isle Lab And Mfg Inc Self-extinguishing asphalt composition
US2866900A (en) * 1955-12-19 1958-12-30 Itt Nondispersive infrared analyzer
US2868062A (en) * 1956-12-03 1959-01-13 Hillside Lab Optical device for testing absorption
US2940360A (en) * 1957-05-23 1960-06-14 Jr William H Carter Perfusion chamber
US2979410A (en) * 1957-05-13 1961-04-11 Tee Pak Inc Food package and packaging film therefor
US3001073A (en) * 1957-05-23 1961-09-19 Industrial Nucleonics Corp Reflectivity comparison system

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1014601A (en) * 1911-11-28 1912-01-09 Matthew M Looram Receptacle.
US2667425A (en) * 1950-02-02 1954-01-26 Presque Isle Lab And Mfg Inc Self-extinguishing asphalt composition
US2866900A (en) * 1955-12-19 1958-12-30 Itt Nondispersive infrared analyzer
US2868062A (en) * 1956-12-03 1959-01-13 Hillside Lab Optical device for testing absorption
US2979410A (en) * 1957-05-13 1961-04-11 Tee Pak Inc Food package and packaging film therefor
US2940360A (en) * 1957-05-23 1960-06-14 Jr William H Carter Perfusion chamber
US3001073A (en) * 1957-05-23 1961-09-19 Industrial Nucleonics Corp Reflectivity comparison system

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452193A (en) * 1965-04-19 1969-06-24 Weyerhaeuser Co Moisture content measuring method and apparatus
US3512895A (en) * 1967-02-06 1970-05-19 Eastman Kodak Co Spectroreflectrometric reference standard and method
US3478210A (en) * 1967-08-23 1969-11-11 Gen Electric Extended range infrared moisture gage standards
US3641349A (en) * 1969-09-29 1972-02-08 Measurex Corp Method for measuring the amount of substance associated with a base material
US3631246A (en) * 1970-04-30 1971-12-28 Shell Oil Co Method for determining the purity of recovered sylvite
US3790796A (en) * 1972-06-05 1974-02-05 Infra Systems Inc Method and apparatus for measurement of sheet opacity
US4037970A (en) * 1972-08-24 1977-07-26 Neotec Corporation Optical analyzer for agricultural products
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DE1498762A1 (de) 1969-04-10
NL6402829A (de) 1964-09-22
GB1055111A (en) 1967-01-18
SE315761B (de) 1969-10-06

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